Four-object-oriented-class library, delegate

VAR Universal variable:
var a = value/constructor instantiation;
Given what type of data it is, it automatically becomes the appropriate type and does not require a type conversion.

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Class Library:
1. A. cs source code file, sent over,
Add in your own project, reference namespaces, invoke methods;

Generally used within the company, because the source code files can be seen, and can be modified;

(This is not a class library)

Namespace consoleapplication1{    class Suanshu {//<summary>////        </summary >//        <param name= "A" > First number </param>//        <param name= "B" > Second number </param>//        < returns></returns> public        int Jiafa (int a, int b)        {            return a + b;        }        public int Jianfa (int a, int b)        {return a-a            ;        }    }

Namespace Class Library {    class program    {        static void Main (string[] args)        {            var a = ten;            var B = 20;            

            
            Console.WriteLine (c);

            
        }

2. Class Library Mode:
A class library, is a DLL at the end of the file, is the source code after the compilation of auxiliary files;----This file can be referenced, cannot read the modified
After you add a reference to your project, reference the corresponding namespace,
You can instantiate a common class in a class library, and you can call public methods

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Commissioned:
Is the agent, the event is also a delegate, but is a special delegate;
1. Declaring the delegate type:

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public delegate int Firstdel (int a, int b)

2, the definition of the delegate variable and the assignment value:

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public int Jiafa (int a, int b)        {            return a + b;        }
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Firstdel f1 = new Fangfa (). Jiafa;            int c = f1 (5, 4);

3, the use of the delegate variable:

Namespace delegate {public    delegate int Firstdel (int a, int b);//Declare delegate type    class program    {        static void Main (Strin G[] args)        {            Firstdel f1 = new Fangfa (). Jiafa;            int c = f1 (5, 4);            Console.WriteLine (c);            Firstdel F2 = new Fangfa (). JIANFA;            c = F2 (5, 4);            Console.WriteLine (c);            c = F1 (5, 4) + F2 (5, 4);            Console.WriteLine (c);            Console.readkey ();        }    }

Namespace Delegate {    class Fangfa    {public        int Jiafa (int a, int b)        {            return a + b;        }        public int Jianfa (int a, int b)        {return a-a            ;        }

Four-object-oriented-class library, delegate